What term describes a river or stream that flows into a larger river or lake?

The term that accurately describes a river or stream that flows into a larger river or lake is "tributary." A tributary is a smaller body of water that contributes its flow to a larger body, enhancing the overall water volume and affecting the hydrology of the larger system. Understanding this term is important because it highlights the interconnectedness of water systems and the role of smaller waterways in the ecosystem.

In contrast, a creek typically refers to a smaller stream that may or may not flow into a larger body of water, while an estuary is an area where freshwater from rivers meets and mixes with saltwater from the ocean. A confluence refers specifically to the point where two or more bodies of water meet, but it does not describe the smaller stream itself. Therefore, tributary is the most precise term for a river or stream that flows into a larger river or lake.